Plane spotters mentioned the arrival of OO-SNI in our aviation forums, today the newest Airbus A320 into the Brussels Airlines fleet came in from Prague, were the cabin has been retrofitted.
Before landing at Brussels Airport the A320 made a big turn over The Netherlands, to perform the necessary checks before she enters the fleet.
One particular sound that was noticed on the ground was a “piaggio-like” sound. It is the normal procedure of testing the ram air turbine (RAT)*, member CTBke mentioned in our forum.
Soon OO-SNI will fly through the European skies.
Forum discussion: http://www.luchtzak.be/forums/viewtopic.php?p=352622#p352622
* A ram air turbine (RAT) is a small turbine that is connected to a hydraulic pump, or electrical generator, installed in an aircraft and used as a power source. The RAT generates power from the airstream by ram pressure due to the speed of the aircraft.
Modern aircraft generally use RATs only in an emergency. In case of the loss of both primary and auxiliary power sources the RAT will power vital systems (flight controls, linked hydraulics and also flight-critical instrumentation). Some RATs produce only hydraulic power, which is in turn used to power electrical generators. In some early aircraft (including airships), small RATs were permanently mounted and operated a small electrical generator or fuel pump.
Wikipedia Ram air turbine: https://en.m.wikipedia.org/wiki/Ram_air_turbine